Semiconductor devices in electrical circuits tend to increase in heat generation amount since the semiconductor devices become to have high density and high current. In particular, semiconductors using Si cause malfunction and a failure at an ambient temperature of 100° C. or more. The heat generating components like such semiconductor devices or similar devices include, for example, a switching element such as an Insulated Gate Bipolar Transistor (IGBT) and an Intelligent Power Module (IPM).
To effectively cool the heat generating components, a heat dissipating board with a heat dissipating path is employed. The heat dissipating path is formed on an opposite side from a mounting surface of components at the substrate. Specifically, heat generated from the heat generating component is conducted to a back surface side of the substrate (the opposite side from a component mounting surface (the mounting surface) and the back surface side is cooled with a heat sink or a similar component.
As a method of forming the heat dissipation path, for example, a heat conducting member made of metal of high thermal conductivity (Cu, Al, or a similar element) is disposed in a through hole formed at the substrate. The heat conducting member is secured in the through hole. The metal is secured to the through hole by close-fitting using press-fit and elastic deformation, bonding with an adhesive or a solder, or a similar method (see, for example, Patent Literature 1). The heat generating component is heat dissipated as follows. The heat conducting member is coupled to the heat generating component and the heat generated from the component is heat dissipated to the outside via the heat conducting member (for example, a pillar-shaped copper).